Magnetic resonance imaging, or MRI (see Section 21.7), and positron emission tomography, or PET scanning (see Section 32.6), are two medical diagnostic techniques Both employ electromagnetic waves. For these waves, nd the ratio of the M RI wavelength (frequency = 6.60 X 107 Hz) to the PET scanning wavelength (frequency = 1.14 X 1020 HZ). Number n Units V In a dentist's office an X-ray of a tooth is taken using X-rays that have a frequency of 8.32 x 1018 Hz. What is the wavelength in vacuum of these X-rays? Number i Units